Jim -
I do want to point out that Sylvia was not incorrect for SELV Circuits separated from other SELV Circuits or for SELV Circuits separated from a chassis (there are also other combinations). But Table 5B is somewhat misleading and a review could be incomplete, if other portions of the standard aren't also dutifully applied. In my Points 1-7, I had tried to say, but must have failed, that this requirement is derivable from reviewing Table 2G, Figure 2F, then picking the appropriate insulation, circuits and working voltages from Table 5B. In the specific example I gave, the requirement is for Supplementary Insulation between the ELV Circuit and an unearthed SELV Circuit. This Supplementary Insulation would be subject to the same requirements as if it were placed directly between the Primary Circuit and the unearthed SELV Circuit and applying the appropriate column (two through six) of table 5B. This is not unlike the old method of using two isolation transformers, one to derive an ELV Circuit from a Primary Circuit, the other to derive SELV from the ELV Circuit. In essence, review the insulation required between different circuits, then apply the Clearance, Creepage and EST requirements from them, rather than starting with the test requirement. Regards, Peter L. Tarver, PE Product Safety Manager Homologation Services Sanmina-SCI Corp. 2000 Ringwood Ave. San Jose, CA 95131-1749 V: 408-904-2081 F: 408-904-2095 M: 408-234-3529 [email protected] > From: Jim Eichner > Sent: Monday, December 08, 2003 11:26 AM > > I agree that first principles tell us the hipot > test (EST) in your point 7 > should be required, but where is that stated in > the standard? Table 5b) > seems to be the only place where it says which > insulation needs to tested. > > > > From: Peter L. Tarver > Sent: Friday, December 05, 2003 3:26 PM > > 7) the ELV Circuit to unearthed to the SELV Circuit > requires an EST based on Supplementary Insulation > in one of > the five columns (two through six) of table 5B > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
